Visit the ASRock support page, you should be able to find the model of motherboard there. Most motherboards also come with a driver CD, if you haven't tried that already.
ASRock > Support
Otherwise, under control panel, system and security, then system you will find "device manager" on the left. Right clicking on network adapters and selecting "scan for hardware changes" may put windows into "find a driver for this" mode. Otherwise right click the problematic device (should be a yellow triangle) and select "update driver software."
Post any problems.